Nigeria has been rocked by protests in which one man was killed, authorities fired tear gas and crowds blocked petrol stations to demonstrate against soaring fuel prices.
A top trade union accused police of shooting dead a protester, but authorities strongly denied they were to blame for the killing in Kwara state in the country's central west.
Nigeria ended fuel subsidies on Sunday, which caused pump prices to more than double to about 140 naira (94 Australian cents) per litre in a country where most people live on less than $2 per day.
In the economic capital Lagos, about 200 people, including prominent rights activists and the son of the late legendary musician Fela Kuti, Seun Kuti, began the day protesting before marching along a main highway.
Kuti, whose father was a harsh critic of Nigerian corrupt regimes, launched a verbal attack against President Goodluck Jonathan, telling the crowd that "Jonathan is Nigeria's only terrorist".
"Nigerians cannot pay the same price for petrol as America," he said. "We don't have the American minimum wage."
A small crowd on the margins of the rally burnt tyres and protesters ransacked at least one petrol station, while police fired tear gas to disperse the crowd.
One man claimed to have been hit by a live round and showed journalists a wound to his stomach as he ran away.
Other petrol stations shut down as the protesters sought to block fuel sales.
"We will not leave the streets until fuel prices come back to 65 naira," one person who identified himself as Tunde said earlier as he carried a container of fuel to pour over tyres.
In Kwara, a man was killed, setting off an argument over who was to blame.
"It is with a heavy heart that the Nigeria Labour Congress announces the murder of an anti-fuel price hike protester, who was shot dead by the police today," the union said in a statement.
However, Dabo Ezekiel, Kwara police spokesman, said: "It is not true that he was shot dead by the police."
"The police had no hand in his death," Ezekiel said. "In the course of the protest, he was attacked by the mob who felt that he was not one of them. He was stabbed with a sharp object in the chest and he died."
In Kano, the largest city in Nigeria's north, police moved in quickly to prevent a protest, detaining nine people preparing for a demonstration at a football pitch they renamed "Freedom Square", an organiser said.
"The nine of us, the organisers of the sit-in protest, are now being detained at the police metropolitan division," Audu Bulama said by phone before it was seized by police.
"As we were gathering, 20 armed policemen came in three vans and dispersed the crowds of about 40."
The nine were released a few hours later. Police said they had been brought in for questioning.
Separate protests broke out later, including by a couple of hundred people near the state parliament building in Kano.
In the capital Abuja on Monday police also used tear gas to disperse a protest there. The country's main trade unions have threatened protests for the coming days.
Protest threats in Nigeria have often fizzled out in the past, but the fuel subsidy issue is one of the few that unites much of the vast country, with widespread popular opposition to the move.
Economists and government officials view removing the subsidy as essential to allow for more spending on the country's woefully inadequate infrastructure and to ease pressure on its foreign reserves.
The government says more than $US8 billion was spent in 2011 on fuel subsidies.
Nigerians however see the subsidy as their only benefit from the nation's oil wealth, and years of deeply rooted corruption have resulted in profound distrust of government officials.
